Vulcanization of rubber employing amines and open-chain aldehydes and similar substances and products obtained thereby



UNITED STATES PATENT OFFICE.

SIDNEY M. CADWELL, OF NEW YORK, N. Y., ASSIGNOR TO THE NAUGATUCK CHEMICAL COMPANY, A CORPORATION OF CONNECTICUT.

'VULCANIZATIO N OF RUBBER EMPLOYING AMINES AND OPEN-CHAIN ALDEHYDES AND SIMILAR SUBSTANCES AND PRODUCTS OBTAINED THEREBY.

Specification of Letters Patent.

Patented May 30, 1922.

No Drawing. Continuation of application Serial No. 376,659, filed April 2'6, 1920. This application filed May 28, 1921. Serial No. 473,345.

T 0 all whom it may concern: Be it known that I, SIDNEY M. C'ADWELL, a citizen of the United States, residin in NeW'York, county and State of New ork, have invented certain new and useful improvements in vulcanization of rubber employing amines and open-chain aldehydes and similar substances and products obtained thereby, of which the following is a full, clear, and exact description.

This inventionrelates to vulcanization of rubber or similar materials such as balata, gutta percha and rubber substitutes. It is more particularly directed to the vulcaniza- .benzylidine aniline, formaldehyde aniline and benzylidine ethylamine. It has been found" that these accelerators are relatively inactive and further that the accelerator aldehyde ammonia is unstable and poisonous.

It is accordingly an object of this invention to provide a process for vulcanization employing non-toxic, stable materials ofthe type mentioned, which shall permitthe employment of a shorter time for the same quantity of accelerator than heretofore employed or the employment of a smaller quantity of the accelerator than heretofore employed and approximately the same time. It is also an object of the invention to provide a process-of the type mentioned which will not cause over-vulcanization as readily as with other accelerators heretofore known. Another object of the invention is to pro- -vide a process of the kind described employing materials with which prevulcanization in milling is substantially avoided. An-

other object of the invention is to provide a process of the kind described which shall employ accelerators which may be made of relatively inexpensive raw materials. Another object of the invention is to provide a vulcanized product having good ageing properties, high tensile strength, toughness, freedom from bad odor and freedom from poisonous qualities. Another object of the invention. is to provide a process employing accelerators made from nitrogenous materials such as aromatic amines having a relatively low accelerating value in themselves combined with other materials having in themselves little or no accelerating value, to produce acceleration of great rapidity.

This application is a continuation of my former application Serial No. 376,659, filed April 26, 1920. I

The invention accordingly consists in a process of treating rubber or similar materials which comprises combining the rubber with a vulcanizing ingredient and the reaction product of an open carbon chain aldehyde having a plurality of carbon atoms and an amine and vulcanizing the rubber. The invention also includes the product of such process.

In its preferred embodiment 100 parts of rubber, 10 parts of zinc oxide, 3 parts of sulphur and 0.5 part of the condensation product of aniline and heptaldehyde are mixed togetherby milling on rolls inthe usual manner and vulcanizing in a press under '40 pounds steam pressure for 60' 'ment of the invention 100 parts of rubber,

'10 parts of zinp oxide, 3 parts of sulphur and 0.5 part of the reaction product of acetaldehyde and aniline are mixed together and compounded by milling in the usual manner. The resulting mixture may be cured in a mold with steam at 40 .pounds pressure for 60 minutes.

Equal weights of aniline and water are mixed and an excess of acetaldehyde. are run in while the mixture is stirred vigorously. When reaction is complete the water and excess chemicals are evaporated ofi' preferably in vacuum using steam to furnish the heat. The residue is heated until it has a consistency thatv will soften under the continued pressure of the hand and fracture if struck a sharp blow.

The roducts of reaction between aniline and heptaldehyde and aniline and acetaldehyde are examples of a large. number of similar substances which may be similarly employed in the vulcanization of rubber.

The processes for employing these various materials are substantially identical with those already set forth, that is a typical process consists in mixing 100 parts of rubber, 10 parts of zinc oxide, 3 parts of sulphur, and 0.5 part of the reaction product of the aldehyde and amine, and vulcanizing under 40 lbs. pressure for 60 minutes. The propor- 'tions mentioned in this formula may be produce variously comexamples given the thicknesses of materials are generally about The similar substances are as follows: Acetaldeh de meta nitraniline, acetaldehyde benzidlne, acetaldehyde metatoluylene diamine, acetaldehyde 'triamidotoluol, acetaldehyde hydroxylamine,v phenylhydrazene, polyheptylidine aniline, duodecylidine aniline, stearic aldehyde aniline, octylaldehyde' aniline, nonyl'aldehyde aniline, heptaldehyde para luidine, heptaldehyde naphthylamine, isob tylaldehyde aniline, cinnamaldehyde aniline, citronellal aniline, valeraldehydeaniline, propionaldehyde aniline, he taldoxime, dextrosazone, glucose aniline, g ucose ammonia, acetaldehyde monomethylaniline, acetaldehyde aniline, acetaldehyde o-toluidine, acetaldehyde -p-toluidine, acetaldehyde p-phenylenediamine butylaldehyde p-toluidine, butylaldehyde aniline, acetaldehyde urea, acetaldehyde B-naphthylamine, acetaldehyde p-ni acetaldehyde traniline, acetaldehyde diphenylamine, acetaldehyde acetphenylenediamine, heptaldehyde diethylamine, heptaldehyde benzylamine, cinnamaldehyde ethylamine, heptalthe tensile strengths of similar rubber similarly compounded. With formaldehyde aromatic amine condensates it will be found thatthe tensile strengths of the materials employed in the present invention are approximately 33% greater than such condensates when,'for example, the preferred embodiment' is employed. Tensile strengths obtained in rubbers by the present invention are about greater than those produced by aromatic aldehyde aromatic amine condensates produced and tested under similar conditions. In order to produce as high tensilestrengths inthe rubber products of the formaldehyde and aromatic amine and aromatic aldehyde amine condensates, it is necessary to use much larger quantities of these accelerators, The processes of the present invention are hence less expensive and more efiicient in their reaction than the other processes noted.

It is pointed out that the accelerators mentioned may in general be prepared by treating any primary or secondary amine with the aldehyde in any solvent and is0lat ing the resulting product.- The reaction should not be carried out in strong acid solution. The product usually obtained is an oil but it is possible to prepare certainof the compounds in pure crystalline form.

' Their preparation in the form of an oil is preferable since an oil is more 'easily incorporatedwith rubber. It will be understood that applicant does not intend-to limit reaction products. It is pointed out for example that in the condensates of acetaldehyde orthotoluidine more than one reaction product may be formed and accelerating action may be due in part at least to one or moreof these products. I i

It will be observed that the products list ed above are in general combinations of primary. and secondary amines and straight -more satisfactorily than other members of the group:

Polyheptylidine aniline, heptaldehyde ara toluidine, heptaldehyde naphthylamine, cinnamaldehyde aniline, citron'llal aniline, valeraldehyde aniline, propionaldehyde aniline, acetaldehyde monomethylaniline, acetaldehyde aniline, acetaldehyde o-toluidine, acetaldehyde p-toluidine, acetaldehyde p-phenylenediamine, butylaldehyde p-toluidine, butylaldehyde aniline, heptaldehyde diethylamine, heptaldehyde benzylamine, cinnamaldehyde ethylamine, heptaldehyde methylamine, heptaldehyde ethylamine, valeraldehyde ethylamine, propionaldehyde ethylamine,

hydrocarbon chain,

acetaldehyde benzylamine, acetaldehyde methylamine, butylaldehyde ethylamine, butylaldehyde diethylamine, acetaldehyde ethylamine, acetaldehyde diethylamine.

Observing these results of acceleration as evidenced by the tensile strength it appears that the preferred members of the list'of products given are products of primary and p secondary amines having an electrolytic dissociation constant determined in water greater than 1x10 combined with aldehydes having the aldehyde group attached to a carbon which is not a member of a ring an constituting one of a series of carbons in a the carbon atoms in this chain ranging in number from 2 to 7 It is pointed out that'the process of acceleration may be carried out as set forth in my co-pending application Serial No. 376,659, filed April 26, 1920, that is the inredients that constitute the accelerator may be added separately for example aniline and heptaldehyde may be combined separately with portions of rubber, and the separate ortions may then be mixed and vulcanized. If desired the various accelerators herein mentioned may be combined with sulphur prior to the combination thereof with rubber by heating equal weights of sulphur and accelerator used at abodt 140 C. for 2 hours or more, hydrogen evolved. The resulting product accelerates vulcanization of rubber in a manner similar toacceleration produced employing the roducts listed above. I

It will be observed in the examples given above that zinc oxide has been empl.e ,e with other materials for acceleration. The zinc oxide may be omitted however but if omitted the time of vulcanization is preferably slightly lengthened. An example of bined with heptaldehyde and various 0th sulphide beingv such a vulcanization is as follows: 100 parts of rubber, 8 parts of sulphur, 0.5 parts of the condensation product of heptaldehyde and aniline are mixed on the rolls in the usual manner and cured in a mold under pressure for 7 5 minutes.

Instead of adding an amine with heptaldehyde or other similar aldehyde as herein set forth, the amine naturally occurring in the rubber may be used to cause with the aldehyde a rapid acceleration. 100 parts of a rubber in which substantially the normal amine content of the latex has been retained, 10 parts of zinc'oxide, 3 parts of sulphur and 1 part of heptaldehyde are mixed on the rolls in the usual manner and cure under 40 pounds steam pressure in a press for 60 minutes.

The process employing the accelerators heretofore set forth in general permit a smaller quantity of accelerator to be employed for vulcanization in a time approx1- mately the same as that heretofore employed in connection with the formaldehyde amine condensation products etc. heretofore mentioned. Similar processes of the invention will permit the vulcanization of rubber in a shorter time if quantities of the accelerator are employed equal to that ordi- "narily employed heretofore with formaldehyde amine condensation products etc. The resent process further substav tially avoids over-vulcanization and shows no tendency to prevulcanization when the rubber is milled on hot rolls in the usual manner. It will be observed that the process employs (1 reaction products made from materials which in themselves are inexpensive and cause little or no acceleration. For example aniline, which is relatively inexpensive compared with the aliphatic amines, ,tutes a relatively slow accelerator, is comer aldehydes which in themselves accelerate little if any, to provide rapid accelerators. The accelerators themselves employed are made from relatively inexpensive raw materials. The rubber products produced by the processes of this invention present valuable physical properties such as good resistance to ageing, good resilience, high tensile strength, freedom from odor and freedom from toxicity.

' As many apparently widely bodiments of this invention may difierent embe made and constiwithout departing'from the spirit thereof,

Having thusdescribed my invention, what (1 that I do not intend to I I claim and desire Patent is:

1. A-process for treating rubber which to protect by Letters comprises combining rubber with a vulcanizing agent and the reaction product of an aldehyde comprising an open chain having a plurality of carbon atoms, and an amine, and vulcanizing the rubber.

2. A process for treating rubber which comprises combining rubber with a Vulcanizing agent and the reaction product of an aldehyde having 7 carbonatoms in a straight hydrocarbon-chain, and a nitrogenous material, and vulcanizing the rubber.

comprises combining rubber with a vulcanizing agent and the reaction product of heptaldehyde, and an amine, and vulcanizing the rubber.

5. A process for treating rubber which comprises combining rubber with a vulcanizing agent and the reaction product of a Y straight chain aldehyde having a plurality A vulcanizing the rubber.

of carbon atoms, and a cyclic amine, and vulcanizing the rubber.

6. A process for treating rubber which comprises combining rubber with a vulcanizing agent and the reaction product of an aldehyde comprising a straight hydrocarbon chain having a plurality of car on atoms, and an aromatic amine, and vulcanizing the rubber.

7. A process for treating rubber which comprises combining rubber with a vulcanizing agent and the reaction product of an aldehyde comprising a straight hydrocarbon chain having a plurality of carbon atoms and an amine having an-electrolytic dissociation constant greater than 1 10- and vulcanizing the rubber.

8. A process fortreating rubber which comprises combining rubber with a vulcanizing agent and. the reaction product of an aldehyde having 2 to 7 atoms In a straight. cyclic amine, and,

hydrocarbon chain, and a 9. A process for treating rubber which comprises combining rubber with a vulcanizin agent and the reaction product of an alde yde having 2 to 7 atoms in a straight hydrocarbon chaln, and an amine having an electrolytic dissociation constant greater than 1X10, and vulcanizing the rubber.

10. 'A process for treating rubber which comprises combining rubber with a vulcanizing agent and the reaction product of an aldehyde having 2 to 7 atoms in a straight hydrocarbon chain, and an aromatic amine, and vulcanizing the rubber.

.the rubber.

11. A process for treating rubber which comprises combining rubber with a vulcanizing agent and the reaction product of heptaldehyde, and an aromatic amine, and vulcanizing the rubber.

12. A process for treating rubber which comprises combining rubber with a vulcani'zing agent and the reaction product of 'heptaldehyde, and aniline, and vulcanizing 13.,A process for treating rubber which comprises combining rubber with a vulcan-' izing agent and the reaction product of acetaldehyde, and an aromatic amine, and

vulcanizing the rubber.

. 14. A process for treating rubber which comprises-combining rubber with a vulcanizing agent and the reaction product of aeetaldehyde and aniline, and vulcanizing v 1 the rubber. 4. A process for treating rubber whlch 15. A process for treating rubber which comprises combining rubber with a vulcanizing agent and the reaction product of an aldehyde comprising a straight hydrocarbon chain having a plurality of carbon atoms and an aliphatic amine, and vulcanizing the rubber.

16. A process for treating rubber which comprises combining rubber containing amine as a normal constituent with aldehyde, and vulcanizing the rubber.

17. A process for treating rubber which comprises combining rubber containing amine as a normal constituent with heptaldehyde, and vulcanizing the rubber.

18. .A rubber derived from rubber or similar materials combined with the reaction product of an aldehyde comprising a hydrocarbon chain having a plurality of carbon atoms, and an amine, and vulcanized.

19. A rubber derived from rubber or similar materials combined with the reaction product of an aldehyde having 2' to 7 carbon atoms in a straight hydrocarbon chain, and an amine, and vulcanized.

20; A rubber derived from rubber or similar materials combined with the reaction product of an aldehyde having 7 carbon atoms in a straight hydrocarbon chain, and a nitrogenous material, and vulcanized.

21. A rubber derived from rubber or similar materials combined with the reaction product of heptaldehyde, and an amine, and vulcanized. I

22. A rubber derived from rubber or similar materials combined with the reaction product of a straight chain aldehyde having a plurality of. carbon atoms, and a cyclic amine, and vulcanized.

a plurality of carbon atoms, and an aromatic amine, and vulcanized.

24. A rubber derived from rubber or simihaving a plurality lar materials combined with the reaction product of a straight chain hydrocarbon of carbon atoms, amine having an constant greater than 1 1O' canized.

25. A rubber and vulderived from rubber or similar,materials combined with the reaction in a straight hydrocarbon chain,

2 to 7 atoms product of an aldehyde having and a cyclic in a straight hydrocarbon chain, amine, and vulcanized.

26'. A rubber derived from rubber or similar materials combined with the reaction product of an aldehyde having 2m 7 atoms in a straight hydrocarbon chaln, and anamine having an electrolytic dissociation constantgreater than 1X10, and vulcanized.

27. A rubber derived from rubber or similar materials combined with the reaction.

7 atoms product of an-aldehyde having 2 to and an aromatic am ne, and vulcanized. v

28. A rubber derived from and an electrolytic dissociat1on rubber or simi-r lar materials combined with the reaction product of heptalclehdye, and an aromatic amine, and vulcanized.

29. A rubber derived lar materials combined product of heptaldehdye, vulcanized.-

30. A rubber derived from rubber or similar materials combined-with the reaction product of acetaldehyde, and an aromatic amine, and vulcanized. v

31. A rubber derived from rubber or similar materials combined with the reaction product of acetaldehyde, and aniline,.and vulcanized,

32. A rubber derived from rubber'or similar materials combined with the reaction product of an aldehyde comprising a straight hydrocarbon chain havlng a plurality of carbon atoms, and an aliphatic amine, and vulcanized.

Signed at New York, N. Y., this 26 day of from rubber or simi-' with the reaction. and'anihne, and 

